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## Neil deGrasse Tyson On How To Stop a Meteor Hitting the Earth520

An anonymous reader writes "Astrophysicist Neil deGrasse Tyson talks stopping extinction-level meteor hits: '...Here in America, we're really good at blowing stuff up and less good at knowing where the pieces land, you know...So, people who have studied the problem generally – and I'm in this camp – see a deflection scenario is more sound and more controllable. So if this is the asteroid and it's sort of headed toward us, one way is you send up a space ship and they'll both feel each other. And the space ship hovers. And they'll both feel each other's gravity. And they want to sort of drift toward one another. But you don't let that happen. You set off little retro rockets that prevent it. And the act of doing so slowly tugs the asteroid into a new orbit.'"
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## Neil deGrasse Tyson On How To Stop a Meteor Hitting the Earth

• #### Need some advance planning (Score:4, Insightful)

on Sunday March 03, 2013 @11:58AM (#43061445)
If you are going to use this method, then the more mass in your ship the better. Unfortunately, that means a more expensive launch. If you plan ahead, you figure out a way to accumulate debris and smaller rocks at some stable orbital point so when you need mass you can launch a light ship, go to the rockyard, and gather up more mass at reduced cost.
• #### Re: (Score:2)

The basic problem that I'm seeing is that if you're talking ELE it's a big rock, you're going to need a big mass to pull it off course. Coming to a position of relative rest quickly takes a lot of energy. The smaller the attractor ship, the earlier it has to get into position. But the larger the attractor ship, the more energy it will take to bring it to "rest". I'm still seeing impactors as the logical answer. You could collect rocks at stable points and then fire them at the mass.

If you could work out som

• #### Re: (Score:2)

A tiny nudge early enough just might be enough.

• #### Re: (Score:2)

A tiny nudge early enough just might be enough.

Better off, then, sending an impactor that goes splat. And either way, we don't tend to know that early whether it will hit or not. Right now we would have to send our hypothetical craft to rendezvous with every potential impactor, because otherwise we wouldn't even know if we needed to deflect them. So it's not really a workable idea without dramatically improving our detection network...

• #### Re: (Score:2)

Another method is to place a very powerful laser in orbit around Earth or another suitable orbit and then fire at the asteroid. If the laser is powerful enough it will cause the asteroid to shed some material and through that slightly change the orbit. This will work fine given enough time and precise enough calculations.

The problem by having a spaceship approaching an asteroid is that it requires a lot of fuel to get there. In addition to that there's no easy way to beforehand get enough information about

• #### Great caution is Advised (Score:2)

If you change its orbit, the meteor may be set on a collision course in a later go-around. What you want to do is change its orbit so all future approaches are farther from impacting earth, not just this time. Another-words, pay attention to what you are doing. Do not just do something short term.

• #### Re: (Score:3)

All you have to do is generate a near miss once and the rock's orbit will be radically altered forever after, by the slingshot effect of Earth's own gravity as it passes by. Remember 2012 DA14? It will never pass so close to us again. When it went by that close, it got slung into a new orbit.

• #### Why is "blow the thing up" a bad idea? (Score:5, Interesting)

on Sunday March 03, 2013 @12:22PM (#43061613)

"Knowing where the pieces land" seems like a red herring.

If we detect an asteroid a long way out on a collision course with Earth, then altering its velocity by just a bit will push it off of course and it'll miss us. If you set off an explosion near an asteroid, it will indeed likely fragment, but the only way we're still getting hit is if a large chunk somehow gets *no* delta-v from the explosion, and if that chunk is big enough to survive reentry.

OTOH, if we detect a big asteroid close to us, there may not be time for these things, and we need a large impulse quickly.

Either way, "nuke it" seems like the most sensible thing. Yes, this is a drastic thing, but if it's a true doomsday asteroid then it's called for.

• #### Re: (Score:3)

You really want to avoid any pieces going even near orbit. We have a mess of expensive stuff up there.

Honestly, nudging it off course with some ion drives or any source of contained thrust is a good idea. Nuking it is only better than an extinction level event. Such as last minute, too large, etc. Where humanity will still probably be largely hosed, but not completely. Even if you converted a large mass asteroid to sand, it'd still do not-great things.

Buddy of mine with a bunch of engineering degrees
• #### Re:Why is "blow the thing up" a bad idea? (Score:4, Insightful)

on Sunday March 03, 2013 @04:30PM (#43063199)

You really want to avoid any pieces going even near orbit. We have a mess of expensive stuff up there.

It is not difficult to choose between "survival of the planet" and "doing without TV and GPS for a few years".

• #### Conversation of energy (Score:3)

on Sunday March 03, 2013 @12:23PM (#43061621)

Wouldn't it just be better to smack into one side of the asteroid at full speed rather than use a bunch of energy to get to the asteroid, a bunch more to slow down and rendezvous, then use little puffs of energy to try and modify its orbit?

Seems to me that all that reaction mass would be much better served by hitting the rock traveling at 4X,000 MPH.

• #### Re: (Score:2)

For the same launch mass an impact should result in a much larger change of orbit than if the orbit is changed with a rocket. There is no need to accelerate to th speed of the asteroid, the impactor just has to cross its orbit. And the impulse change resulting from the impact of a certain weight is probably larger than anything we can achieve with a rocket of the same weight. The actual impulse of any chemical rocket fuel colliding with an asteroid is larger than the specific impulse that it can generate wh
• #### Setting the record straight) (Score:2)

The idea of using gravity (the proper name is Gravity Tractor) to deflect incoming rocks has been around for some years now - and it wasn't Neil's idea.

• #### My 0.02 (Score:2)

Let the meteor come!
• #### Deflection is Rehashing Old Ideas (Score:4, Funny)

on Sunday March 03, 2013 @01:21PM (#43062093) Journal
Mr. Miyagi [imdb.com]:

Remember, best block, no be there.

If Sam Kinison [wikiquote.org] were alive today, he'd apply his philosophy on world hunger and say:

You want to help end extinction-level meteors? Stop sending up shit to blow them up. Don't send them another one, send up huge orbit-altering rockets. Send the UN a guy that says, "You know, we've been coming up with a plan to blow up meteors for about 35 years now and we were blowing stuff up, and we realized there wouldn't BE extinction-level meteors if you people would live where the METEORS AREN'T! YOU LIVE INSIDE AN ASTEROID BELT!! UNDERSTAND THAT? YOU LIVE IN A FUCKING ASTEROID BELT!! Stop wasting rockets by launching them at each other. You too, North Korea... don't give me that look. We're going to do this together in one shot.

The most-effective solution is don't be where the meteor is going to be. This worked well for me the other week. Giant meteor fell in Siberia and I wasn't there.

• #### After reading the comments at the CNN article... (Score:4, Insightful)

on Sunday March 03, 2013 @01:56PM (#43062329) Homepage

.... I'm confident that we have little to worry about. Asteroids will tend to avoid our planet out of sheer embarrassment.

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